Human joints, in particular the knee, hip, ankle, shoulder, and spine, are susceptible to degeneration from disease, trauma, and long-term repetitive use that eventually lead to pain. Knee pain, for example, is the impetus for a wide majority of medical treatments and associated medical costs. Osteoarthritis (OA or degenerative arthritis) is the most common joint disorder known. Osteoarthritis is characterized by cartilage loss at the joint, and symptoms generally include pain and stiffness. The disease can affect all joints of the body, including the hip, shoulder, ankle, and spine, to name a few. One form of the disorder, osteoarthritis of the knee, is a common and rapidly growing problem amongst U.S. adults. Knee osteoarthritis often causes severe pain and is associated with loss of function leading to a diminished quality of life. Knee osteoarthritis can be defined by the thinning, softening, fissuring, fibrillation, and eventual loss, of cartilage covering the surface of the bones in the knee joint. In the early stages of the disease process, this loss of cartilage may cause minimal pain and often those afflicted are asymptomatic. Unfortunately, the natural history of knee OA usually is progressive, leading to the significant symptoms and problems already described.
Patients most often seek treatment because of pain and deterioration of quality of life attributed to the osteoarthritis. The main goal of osteoarthritis treatments is to reduce or eliminate pain, and restore normal joint function. Both non-surgical and surgical treatments are currently available for this purpose, with the appropriate treatment being selected based in part on the stage and/or severity of the disease.
Non-surgical treatments for knee osteoarthritis include weight loss (for the overweight patient), activity modification (low impact exercise), quadriceps strengthening, patellar taping, analgesic and anti-inflammatory medications, injections, and with corticosteroid and/or viscosupplements. Typically, non-surgical treatments, usually involving pharmacological intervention such as the administration of non-steroidal anti-inflammatory drugs or injection of hyaluronic acid-based products, are initially administered to patients experiencing relatively less severe pain or joint complications. However, when non-surgical treatments prove ineffective, or for patients with severe pain or bone injury, surgical intervention is often necessary.
Surgical options include arthroscopic partial meniscectomy and loose body removal. Most surgical treatments conventionally employ mechanical fixation devices such as screws, plates, staples, rods, sutures, and the like are commonly used to repair damaged bone. These fixation devices can be implanted at, or around, the damaged region to stabilize or immobilize the weakened area, in order to promote healing and provide support. Injectable or fillable hardening materials such as bone cements, bone void fillers, or bone substitute materials are also commonly used to stabilize bone defects.
One type of surgical treatment focuses on unloading forces from the damaged joint. Another type of surgical treatment aims to replace, either partially or wholly, the damaged area of the joint. For example, one surgical treatment seeks to replace the damaged or worn cartilage by way of cartilage resurfacing or cartilage replacement. Other surgical treatments, such as high tibial osteotomy (HTO) or total knee replacement (TKR) or arthroplasty (TKA), are often recommended for patients with severe pain associated with osteoarthritis, especially when other non-invasive options have failed. Both procedures have been shown to be effective in treating knee pain associated with osteoarthritis, at least in the short term.
These treatments are based on the popular theory within the medical community that knee pain results from bone-on-bone contact or inadequate cartilage cushioning. These conditions are believed to frequently result from the progression of osteoarthritis, which is measured in terms of narrowing of the joint space. Therefore, the severity of osteoarthritis is believed to be an indicator or precursor to joint pain. Most surgeons and medical practitioners thus base their treatments for pain relief on this theory. However, the severity of osteoarthritis, especially in the knee, has been found to correlate poorly with the incidence and magnitude of knee pain. Because of this, surgeons and medical practitioners have struggled to deliver consistent, reliable pain relief to patients, especially if preservation of the joint is desired.
In some instances, the joint pain recurs in patients after partial or total joint replacement surgery after some time. This is generally believed to be due to the disease state advancing beyond the benefits of the initial joint replacement treatment. Accordingly, better treatment options are still needed for patients suffering from joint pain, particularly due to osteoarthritis and other degenerative diseases, to address the various stages of the disease and provide a more complete treatment over the continuum of the disease's natural progression.